Hi Joanie,
16 eggs is probably too many. I prefer to hatch fewer eggs (7 for my
full-size hens) rather than more and loose some because of chilling.
The hen needs room to maneuver the eggs so the outer ones are rotated
to the middle, and vice versa. It's also easier to take care of and
monitor fewer eggs.
I've been doing some research and experimenting with using hens to
incubate eggs and brood chicks naturally. The reason for a broody box
is more to keep other hens out from laying eggs with the fertile ones
rather than to keep the broody hen in. Marking eggs with a pencil or
wax pencil helps you identify which eggs are which.
I've also found that the broody hens like (and deserve) a break from
the broody box. I always let them out if they are off the clutch
wanting to get out. That just about always means they need to poop
and don't want to get the nest dirty.
Around 3 to 4 in the afternoons, or before dark if I get home later,
I'll just open the door to the broody box (a medium to large pet
carrier) and let them out. They roam around, stretch, eat and take
dust baths. After about 30 minutes or so, they return to the nest on
their own. I've never not had a hen return to the clutch after a break.
If you don't let them have a break then you will need to put fresh
bedding in the nest and remove soiled bedding. It's easier just to
open the door if it is convenient for you to do so.
Hope this helps.
Pat Foreman